We present K-band interferometric observations of the PDS 70 protoplanets
along with their host star using VLTI/GRAVITY. We obtained K-band spectra and
100 μas precision astrometry of both PDS 70 b and c in two epochs, as well
as spatially resolving the hot inner disk around the star. Rejecting unstable
orbits, we found a nonzero eccentricity for PDS 70 b of 0.17±0.06, a
near-circular orbit for PDS 70 c, and an orbital configuration that is
consistent with the planets migrating into a 2:1 mean motion resonance.
Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS
70 b of 10 MJup, while the mass of PDS 70 c was unconstrained. The
GRAVITY K-band spectra rules out pure blackbody models for the photospheres of
both planets. Instead, the models with the most support from the data are
planetary atmospheres that are dusty, but the nature of the dust is unclear.
Any circumplanetary dust around these planets is not well constrained by the
planets' 1-5 μm spectral energy distributions (SEDs) and requires longer
wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made
the first observations of a circumplanetary environment with sub-au spatial
resolution, placing an upper limit of 0.3~au on the size of a bright disk
around PDS 70 b